Escalating sabotage against pipelines in Iraq is heightening fears that terrorists are planning a wholesale assault on energy targets throughout the region and are taking aim at the world's largest oil supplier -- Saudi Arabia.

The head of Saudi Arabia's government oil monopoly remains confident that the industry is well protected. But independent experts warn that an attack on any of Saudi Arabia's major facilities could cripple world oil supplies.

So far, a year's worth of terrorist attacks have had little impact on the Saudi industry. While gunmen linked to Al Qaeda struck in May at oil hubs on both sides of the kingdom, killing five people at an oil export facility on the Red Sea and 22 in Khobar in the heart of Saudi Arabia's petrochemical industry along the Persian Gulf, neither attack directly hit oil facilities.

But many experts warn that the country's pipelines, oil wells, refineries and export terminals are enticing targets for Al Qaeda, whose operatives in Saudi Arabia are threatening to launch a devastating attack. They watch with concern the attacks on oil facilities in Iraq, where insurgents assassinated a top oil security executive and blew up a critical pipeline Wednesday, halting exports.

Extensive terrorist attacks on oil targets in Saudi Arabia and Iraq would be tantamount to "an energy Pearl Harbor," forcing severe shortages and boosting prices in the United States and other countries heavily dependent on imported oil, said Anne Korin, a senior analyst with the International Institute for Analysis of Global Security in Rockville, Md.

The United States gets more than 50 percent of its oil from foreign suppliers. The terrorists "can hit the homeland without ever leaving their own backyard," Korin said.

Others expect an escalation in attacks.

"It's not as bad as it's going to get," said Danny Clayton, who helped extinguish 737 wells set ablaze by Saddam Hussein's forces during the 1991 Persian Gulf War.

Clayton, who is a manager of the Houston-based firefighting company Boots & Coots International Well Control, said terrorists can easily disable a section of remote desert pipeline with a well-placed explosive charge or even a single bullet in the pipe.

"It's going to happen," he said. "It's the growing trend at the moment."

Korin also said she thinks a 9/11-style attack, in which an airplane would crash into an oil terminal or refinery, is a possibility.

The president and chief executive officer of Saudi Aramco said his company is prepared to prevent such an attack. Abdallah Jumah described an elaborate security net that includes surveillance cameras, bomb-sniffing dogs, more than 5,000 guards and thousands of government security forces, aerial surveillance and patrols of the waters near exporting facilities.

Backup systems can keep the oil flowing smoothly even if a section of pipeline or unit in a refinery is disabled.

"Our system has so much resilience that we would be able to carry on," said Jumah, who has been the energy company's chief since 1995.